Method of sealing a bag



R. E. WALTON METHOD OF SEALING A BAG June 20, 1967 Filed Sept. 2, 1964 United States Patent O 3,325,963 METHOD GF SEALING A BAG Robert E. Walton, 1308 East Ave., Worthington, Minn. 56187 Filed Sept. 2, 1964, Ser. No. 395,356 3 Claims. (Cl. 53-29) The present application is a continuation-in-part of my copending application, Ser. No. 192,372, led May 4, 1962, and now abandoned.

This invention relates to an improvement in bag construction and the method `for sealing the bag and deals particularly with a bag construction which may be sealed tightly enough to contain liquids and the like and the method for sealing the liquid-containing bag.

For some time work has been done on developing a paperboard container which may be used as a substitute for metal cans and glass jars in the shipping of liquid or semi-liquid products. Certain of these constructions comprise merely a regular style corrugated container made of corrugated paperboard which contains a separate inner liner formed of relatively light weight paperboard having a liquid tight and heat sealable iilrn either extruded or laminated to the inner surface thereof. Certain of such bags or liners comprise creased sheets which include essentially a rectangular blank which is folded intermediate its ends and heat sealed together along two adjoining edges. This leaves only the fourth side of the bag to be sealed after the contents have been inserted. The creasing is such that the seam connecting the sides of the blank is centrally located between the side Wall panels, resulting in generally triangular aps along the edges of the bag between the side walls and top and bottom bag walls. Furthermore, it is usual practice to insert such a liner into the outer container, to insert the contents, and then to form the top seal by means of a heat sealing unit which may comprise a pair of opposed heated jaws.

In general, this arrangement is extremely effective. The only point at which ditiiculty is experienced in forming an effective seal is at the corner of the bag where the side seam of the bag and the top seam thereof adjoins. When the bag has been filled, and the top of the bag is folded down into a common plane, the adjoining edges `of these top panels form an upstanding ridge which must be sealed together. In this position, the opposed sides of the top panels of the bag include two triangular flaps which must be sealed along a continuation of the upstanding ridge. The sides also include a second pair of triangular flaps which underlie the first pair and are contiguous therewith. The second pair of triangular iiaps on one side are sealed together along extensions of the vertical side seam. The sealed extensions underlie the second triangular flaps and extend beyond the pointed ends of these triangular aps. To form an effective seal, this extended portion must be sealed to the edges forming the ridge. It is at this point where the horizontal portion of one seam must be sealed to an adjoining vertical portion of the other seam that most difficulty occurs. As a result, diti'lculty is found in producing an effective seal at this point by clamping the seam between heated rollers or belts.

It is an object of this invention to produce an effective seal at the point where the horizontal portion of one seam must be sealed to the adjoining vertical portion of the other seam. The corner where the horizontal top seam and vertical side seam come together cannot properly be cut away without leaving a hole at the juncture between the seams. However, I have found that by notching a portion of the corner, the size of the distorted area is greatly reduced, and at least the upper portion of the top seam may be maintained in a common plane throughout its entire length. As a result, the top seam may be sealed either by a jaw type sealer or by a roller type sealer without the previous diiiiculty. While forming the small notch at the juncture of the two seams might appear to be a small change, this small change has virtually eliminated the leakage of the `sealed bags at the point where the greatest difficulty was previously experienced.

A further object of this invention is to provide a method for folding the bag, sealing the bottom and side seams, lling the bag, notching a portion of the corner where the top horizontal and side vertical seams come together, and sealing the top seam so that leakage of the sealed bag is virtually eliminated.

These and other objects and novel features of the present invention will be more clearly and fully set forth in the following specification and claims.

In the drawings forming a part of the specification:

FIGURE 1 is a perspective view of the upper end of a container containing a sealed inner liner, the figure showing the structure just before the container is closed.

FIGURE 2 is a view similar to FIGURE 1 showing the inner liner just after the sealing operation.

FIGURE 3 is an enlarged perspective view showing one end of the seam after the `sealing operation.

FIGURE 4 is a diagrammatic view of the blank from which the liner is formed.

FIGURE 5 is a view of the container shown in FIG- URE 4 after two adjoining edges have been sealed.

FIGURE 6 is an enlarged detail of one of the corners of the folded blank shown in FIGURE 5.

The liner or bag is formed of the blank best illustrated in FIGURE 4 of the drawings. In usual practice, this blank is formed of light weight paperboard such as, for example, liner of perhaps nine-thousandths of an inch in thickness to which a heat scalable lm has either been extruded or laminated. The coating is designed to provide a protection for the paperboard, and to prevent the leakage of the container contents after the container has been sealed. The nature of the film is obviously dependent to some extent on the nature of the contents being contained.

As indicated in FIGURE `4, the bag or liner A cornprises a generally rectangular blank having a central fold line 10 which divides the blank centrally into two sides 11 and 12 which are identical in form and which accordingly will be designated by similar identifying numerals. Parallel fold lines 13 are provided on opposite sides of the central fold line 1t), defining two side wall panels 14 of equal width. Parallel fold lines 1S extend across the blank in equally spaced relation to the fold lines 13 to form a pair of face panels 16 which are also of equal width. Another pair of parallel fold lines 17 extend across the blank near ends thereof, forming side walls 19 which are of equal width and which are equal in width to the side wall panels 14. The ends of the blank outwardly of the fold line 17 form anchoring flanges 29 which will be later sealed together in face contact.

The lower edges of the face panels 16 and the side wall panels which have been described are defined by a fold line 21 which extends longitudinally of the blank. Parallel fold lines 22 also extend longtiudinally of the blank, and are spaced apart a distance equal to the Width of the side walls 14 and 19 to form bottom panels 23 attached to the lower ends of the face walls 16. The fold line 22 is spaced somewhat from the longtudinal edge of the blank to provide a flange 24 extending throughout the length thereof. The top of the face walls 16 and end walls 14 and 19 are also defined by a longitudinally extending fold line 25 and another parallel longtudinally extending fold line 26 spaced from the fold line 25 a dise tance substantially equal to the width of the side walls 14 and 19. The fold line Z6 is spaced from the longitudinal edge of the blank a distance sutiicient to form a longitudinal flange 27 extending throughout 4the length of the blank. The portions of the blank between the fold lines 25 and 26 and which is also between the fold lines 13 and 15 form top panels 29 which are designed to form a top closure for the bag.

Diagonal fold lines 30 diverge inwardly from the junc ture between the center fold line 1@ and the bottom seam fold line 22 across the square areas hingedly connected along the fold line 21 to the end walls 14. Similar diagonal fold lines 31 extend across the square areas hingedly connected to the side walls 19 along the fold line 21, these fold lines 31 extending across the square areas from the intersec-tion of the fold lines 15 and 21. In general, the upper portion of the blank is similarly formed, diagonal fold lines 32 diverge inwardly from the juncture between the center fold line an the seam fold line 26 across the square areas foldably connected to the side walls 14 along the fold line 25. Similar diagonal fold lines 33 emanate from the junctures between the fold lines and 25, and extend across the square areas foldably connected to the side walls 19 along the fold lines 25.

Por the purpose of identification, the diagonal fold lines divide the square areas attached to the end walls 14 into first triangular gusset aps 34 which are connected to the lower ends of the side walls 14, and similar triangular Igusset flanps 35 which are hinged to the side edges of the bottom panels 23 hinged to the lower end of the face panels 16. In a similar manner, the fold lines 31 divide the square areas hinged to the lower ends of the side walls 19 into triangular flaps 36 hinged to the lower ends of the walls 19, and similar tirangular aps 37 hinged to the side edges of the bottom panels 23.

The top of the bag or liner is, in general, similarly formed. The diagonal fold lines 32 divide the square areas connected to the upper edges of the side walls 14 into a pair of triangular flaps 39 which are hinged to the upper edges of the side walls 14 along the fold lines 25, and similar triangular flaps 40 which are hinge-dly connected to the sides of the top panels 29 along extensionsof the foldlines 13. The diagonal fold lines 33 divide the square areas connected to the upper edges of the side walls 19 into triangular gusset flaps 41 which are hinged to the upper edges of the side walls 19 along the fold line 25 and similar triangular flaps 42 which are hinghed to the ends of the panels 29 along extensions of the fold lines 15.

It will be noted that the lower corners of the rectangular blank include small square areas 43 which are located between the lower seam fold line 22 and the longitundinal edge of the blank and between the side wall seam fold lines 17 and the ends of the blank. The upper corners of the blank are also provided with Vareas which normally would be rectangular and which lie between the upper seam fold line 26 and the upper edge of the blank and between the side seam fold lines 17 and the ends of the blank. The outer corners of these normally rectangular areas 44 are provided with generally rectangular notches 45 which actually comprise the improvement in the present invention.

The method for forming the bag comprises the steps of folding the blank along the centerr fold line 10 so that the sides 11 and 12 are superimposed contiguous relation, heat sealing the folded blank below the lower seam line 22 and the bottom of the blank and between the side wall seam fold line 17 and the adjoining edges of the blank. The above steps, as indicated in FIGURE 6 of the drawings, also result in sealing they notched rectangular areas 44. The sealed area is hatched with broken lines so that the area being sealed may be readily noted. The next step is opening the bag; thereby splitting face wall 16 apart, swinging side walls 14 into a common plane and swinging side walls 19 into a parallel common plane. During this operation, the bottom panels 23 are also swung into a common plane, the gusset aps 34 and 35 folding into face contact, and the triangular flaps 36 and 37 similarly folding into face contact. This forms a generally triangular projection extending beyond the side of the bag which triangular projection may be either folded to lie along the back sidewalls or folded to underlie the bottom panels. During this operation, the flanges forming the seam at the bottom of the bag are usually folded at against one of the bottom panels 23 and the flanges 20 forming the side seam or vertical seam likewise folded against one of the side walls 19 so that the corner portions 43 at the bottom of the container also fold along continuations of the diagonal fold lines 31. The next step is placing the bag in the outer container B and filling the bag. Following this the step of sealing the top seam of the bag after it has been lled must be carried out. If the area such as 27 between the topk seam fold lines 26 and the upper edge of the container bag could be folded down against one of the top panels 29 and sealed in this position, the proper sealy could bc readily obtained. However, in order to apply sealing pressure to the top seam, this seam must usually be held in an upright position as illustrated in FIGURES 2 and 3 of the drawings, during this last sealing operation. A better seal can be provided even with sealing bars when the seam anges are upright as illustrated and this position of the seams is essential if the upper seam is to be made between heated rollers or belts. If the upper corners 44 were unnotched, the portions of the seam anges which underlie the triangular flaps 41, 42 must ex upwardly to the end of the vertical seam. As a result, sealing rollers cannot extend along the full length of the anges 27 including the corners 44. However, by providing the notches 45, the distortions between the two ange portions are very greatly decreased, and the upwardly-extending anges may be sealed throughout their length including at least the upper portions of the corner 44. When the flanges 27 are to be sealed together by a pair of opposed clamping bars, the endsvof these bars may extend well across the fold line 1'7 which automatically provide an effective seal due to the fact that corner 44 area has,` been already sealed during the initial sealing operation.

The size of the notches 45 can be varied, and if the seals extend substantially throughout the entire width of the sealing flanges, the notches can be considerably larger than illustrated. However, the distortion in the flanges is materially relieved even where'the notch is of a size equal to perhaps one-third of the length and width of the square areas 44. Obviously, the greater the size of the notches 45, the less distortion will be experienced during the sealing of the top seam.

In accordance with the patent statutes, I have described the principles of construction and operation of my bag construction and I have described the principles and method for sealing the bag; and while I have endeavoredr to set forth the best embodiment thereof and the-best method therefor, I desire to have it understood that changes may be made within the scope of the following claims without departing from the spirit of my invention.

I claim:

1. The method of sealing a bag, the bag including:

a generally rectangular blank of heat scalable material folded to provide a pair of superimposed contiguous bag sides,

said bag sides being similarly creased to provide a rectangular face panel,

rectangular side wall panels hinged to opposite sides of said face panel,

rectangular top and bottom panels hinged to opposite edges of said face panel,

square corner flaps hinged to said side panels and to said top and bottom panels at each corner of said face panels,

seam forming flanges extending continuously along all but the folded edge of said bag sides adapted to form a bottom seam, a side seam and a top seam, and

said square corners flaps being diagonally creased along lines which are directed toward the corners of the folded bag sides,

the method comprising the steps of notchiug the blank corners comprising the intersection of the side flange and top ange to a point terminating short of the junctures of the fold lines connecting said flanges,

folding the blank along its central crease to fold the bag sides in contiguous relation,

applying heat and pressure to the bottom seam and side seam including the notched area, and sealing these seams together,

opening the bag by folding the side Wall panels on each side of the face panels into a common plane, folding the square corner iiaps at the bottom corners of said face panel along said diagonal creases, folding the bottom seam against one of said bottom panels and said bottom corner aps, and folding said side seam against an adjacent side Wall panel and against one top and bottom corner ap,

lling the bag,

closing the bag by folding the top panels into a substantially common plane and folding the top corner flaps along said diagonal creases, While folding said top seam forming flanges in upright face contact,

the portions of said upper seam forming flanges above the center of said notches being substantially flat, and

applying heat and sealing pressure to said top seam forming anges to seal said seam.

2. The method of claim 1 and in which includes cutting said corners to provide generally rectangular notches by cut lines substantially parallel to the fold lines connecting the ilanges forming the top and side seams to said corner flaps with said cut lines terminating in diagonally-spaced relation to the junctures of these fold lines.

3. The method of claim l and in which the blank comprises a sheet of `paperboard having a heat scalable surface thereupon.

References Cited UNITED STATES PATENTS 2,214,997 9/1940 Guyer 53-27 2,339,305 1/1944 Wagner 53-39 X 2,374,793 5/1945 Waters 53-29 2,704,183 3/1955 Stern 229-53 2,837,267 6/1958 Potdevin et al. 229-53 TRAVIS S. MCGEHEE, Primary Examiner.

FRANK E. BAILEY, FRANKLIN T. GARRETT,

GRANVILLE Y. CUSTER, Examiners.

A. E. FOURNIER, D. M. BOCKENEK, R. L. FARRIS,

Assistant Examiners, 

1. THE METHOD OF SEALING A BAG, THE BAG INCLUDING: A GENERALLY RECTANGULAR BLANK OF HEAT SEALABLE MATERIAL FOLDED TO PROVIDE A PAIR OF SUPERIMPOSED CONTIGUOUS BAG SIDES, SAID BAG SIDES BEING SIMILARLY CREASED TO PROVIDE A RECTANGULAR FACE PANEL, RECTANGULAR SIDE WALL PANELS HINGED TO OPPOSITE SIDES OF SAID FACE PANEL, RECTANGULAR TOP AND BOTTOM PANELS HINGED TO OPPOSITE EDGES OF SAID FACE PANELS SQUARE CORNER FLAPS HINGED TO SAID SIDE PANELS AND TO SAID TOP AND BOTTOM PANELS AT EACH CORNER OF SAID FACE PANELS, SEAM FORMING FLANGES EXTENDING CONTINUOUSLY ALONG ALL BUT THE FOLDED EDGE OF SAID BAG SIDES ADAPTED TO FORM A BOTTOM SEAM, A SIDE SEAM AND A TOP SEAM, AND SAID SQUARE CORNERS FLAPS BEING DIAGONALLY CREASED ALONG LINES WHICH ARE DIRECTED TOWARD THE CORNERS OF THE FOLDED BAG SIDES, THE METHOD COMPRISING THE STEPS OF: NOTCHING THE BLANK CORNERS COMPRISING THE INTERSECTION OF THE SIDE FLANGE AND TOP FLANGE TO A POINT TERMINATING SHORT OF THE JUNCTURES OF THE FOLF LINES CONNECTING SAID FLANGES, FOLDING THE BLANK ALONG ITS CENTRAL CREASE TO FOLD THE BAG SIDES IN CONTIGUOUS RELATION, APPLYING HEAT AND PRESSURE TO THE BOTTOM SEAM AND SIDE SEAM INCLUDING THE NOTCHED AREA, AND SEALING THESE SEAMS TOGETHER, OPENING THE BAG BY FOLDING THE SIDE WALL PANELS ON EACH SIDE OF THE FACE PANELS INTO A COMMON PLANE, FOLDING THE SQUARE CORNER FLAPS AT THE BOTTOM CORNERS OF SAID FACE PANEL ALONG SAID DIAGONAL CREASES, FOLDING THE BOTTOM SEAM AGAINST ONE OF SAID BOTTOM PANELS AND SAID BOTTOM CORNER FLAPS, AND FOLDING SAID SIDE SEAM AGAINST AN ADJACENT SIDE WALL PANEL AND AGAINST ONE TOP AND BOTTOM CORNER FLAP, FILLING THE BAG, CLOSING THE BAG BY FOLDING THE TOP PANELS INTO A SUBSTANTIALLY COMMON PLANE AND FOLDING THE TOP CORNER FLAPS ALONG SAID DIAGONAL CREASES, WHILE FOLDING SAID TOP SEAM FORMING FLANGES IN UPRIGHT FACE CONTACT, THE PORTIONS OF SAID UPPER SEAM FORMING FLANGES ABOVE THE CENTER OF SAID NOTCHES BEING SUBSTANTIALLY FLAT, AND APPLYING HEAT AND SEALING PRESSURE TO SAID TOP SEAM FORMING FLANGES TO SEAL SAID SEAM. 